In one aspect, this invention relates to the treatment of catalytic cracking catalysts with an alkali metal compound (so as to alleviate detrimental effects of metal deposits on the catalysts). In another aspect, this invention relates to the use of thus-treated catalysts in a catalytic cracking processes. In a further aspect, this invention relates to a process for catalytically cracking metal-containing oils with a catalyst which has been treated with an alkali metal compound.
The treatment of metal-contaminated zeolite-containing cracking catalysts with alkali metal compounds (for enhancing or restoring the activity of these catalyst and/or to increase the gasoline yield and/or to reduce hydrogen generation when these catalysts are employed in catalytic oil cracking processes) is known under the term of "metals passivation" and has been described in the patent literature (e.g., in U.S. Pat. Nos. 4,331,563, 4,364,847, 4,727,053 and 4,793,911). Also described in several of these patents are processes for catalytically cracking heavy oils to which an alkali metal compound has been added as a passivating agent. In the present invention, a specific alkali metal compound which does not, to any significant extent, thermally decompose during catalytic cracking and/or catalyst regeneration is used as a metals passivating agent.